Extensible sliver and method of production



Patented Nov. 4, 1941 UNITED STATES PATENT OFFICE EXTENSIBLE SLIVER AND METHOD OF PRODUCTION Karl Kiisslinger, Dessau, and Paul Salfert, Wolfen, Kreis Bitterfeld, Germany, assignors, by mesne assignments, to Walther H. Duisberg, New

York, N. Y.

Application March 10, 1938, Serial No. 195,110 In Germany December 15,- 1937 6 Claims.

cutting and others by tearing a continuous bundle or sliver, in each case retaining substantially the original parallel position of the individual fibers.

For example, it has formerly been proposed to convert a continuous bundle of cellulose fibers into an extensible sliver by feeding the bundle continuously and as far as possible without slip through two pairs of rollers having different peripheral speeds; in this case the feeding device has to forward a continuous bundle at a certain speed and to hold it against slip so that it can be subjected to the draft necessary for tearing the sliver. The pair of draft rollers produces such draft by its greater peripheral speed and the fibers of the continuous bundle are individually torn at the weakest points thereof.

Although numerous proposals have been made in the art for improvements in the processes and apparatus involved, it has hitherto not been practically possible to obtain a uniform distribution of staple lengths within the extensible sliver. In consequence these processes have not found any widespread practical application.

None of the inventors, even when he used progressive tearing, has been in a position to give a serviceable working prescription. Thus in the literature there are found proposals which recommend that the continuous fibers should be divided into sections which are of smaller length than corresponds with the distance from the pair of tearing rollers. For a double or manifold tearing the earlier inventors have already recommended that the tearing distance should be primarily adjusted to about double the staple length and only during the second or any further tearing should the distance be adjusted to the desired final staple length. But even this teaching has not sumced because it was not disclosed that the draft regard must be had to the physical constants of the fiber under treatment, especially its extensibility. For example earlier inventors have given the indefinite prescription that any desired draft might be used and in some cases 4-, 5- and 6-fold drafts have been .said to be applicable. Such high drafts are probably derived from the textile art ingeneral; it appeared, however, that in tearing continuous bundles of artificial fibers they are completely useless.

It is therefore an object of the present invention to provide a process of producing an extensible sliver from a bundle of continuous artificial fibers, in which sliver the individual fibers are 'in substantially parallel position and in which substantially all the fibers have a length which is within a certain predetermined range.

A further object is the provision of a method by which a sliver of the kind referred to may be obtained in continuous operation with a minimurn of the power and in a simple and reliable the improvement brought about by the invention when using a multiple stage tearing process.

It has been found that for the distribution of the staple the tension applied in the tearing op eration is of decisive influence. The new teaching is that one has to suit the draft to the existing extensibility in such a manner that the draft only exceeds by a little the limit of extensibility. Taking for instance a fiber which exhibits about 20 per cent extensibility, the lower limit of the draft is about 1.3; as the upper limit there is to be chosen a draft of at most 2 up to 2.5. Any higher draft leads to excessive production of too short fibers, which renders the sliver obtained completely useless for the further working.

By "applying the new teaching to a single stage tearing, it is even then possible to obtain a sliver of useful staple distribution.

Quite especially, however, the new teaching shows an advantageous result in a tearing process in two or more steps in which each individual "draft is adjusted in accordance with the existing extensibility of the fibe with simultaneous adjustment of the tearing distance. With systematic regard to the influence of the draft on the staple distribution in the tearing process the tearing distance and draft can be adjusted in accordance with the existing extensibility and the desired staple distribution. The effect of the new teaching will be explained with reference to the accompanying staple diagrams. Each of these diagrams, is based upon a particular draft,

draft applied is 2.5; Fig.

the values of which as follows: Fig. 1. the 2, it is 2.0; Fig. 3, it is 1.5; Fig. 4. it is 1.3 Fig. 5, it is 1.5; Fig. .6, it is 1.3; Fig. 7, it is 1.7. The a number in each diagram is the length of the staple in milli- .the same kind of fiber having a single titer, of

The

1.4 deniers (lustrous viscose fiber). I is a fiber of about 20 per cent extensibility and the range of 60 to 140 mm. should be considered.

In diagram 1 only a small fraction of the total quantity of fiber (19.7 per cent) is within this region.

Even with a draft of 2.0 (see Diagram No. 2) no essential improvement is produced, for here 28.5 per cent lie in thesaid range.

With a draft of 1.5 (see Diagram No. 3) the number in question is already 38.8 per cent and with a draft of 1.3 (see Diagram No. 4) the figure rises to 66.8 per cent.

In these four diagrams it'is apparent'that an improvement of the fiber distribution is obtained by applying the invention to a single tearing. Y

Figs. 5-7 comprise fiber diagrams by which the eifect of the new process is shown for the tearing of continuous, artificial slivers for working up like cotton, inwhich case fibers between 30 and 70 ms. are still permissible.

Here also the fiber torn has an extensibility of about 20 per cent. There is used the same kind of fiber which yielded the figures for Diagrams 1-4, namely one having a single titer of 1.4 deniers (lustrous). a

Diagram 5 shows the result of the preparatory first tearing with a tearing distance of cms. and a draft of 1.5. correspondingly with the diminution of extensibility by the first drafting operation the draft in the second tearing is diable. For eliminating this undesired fraction of 1 long fibers there is advantageously selected for the third tearing a much higher draft, for'example 1.7, as shown in Diagram 7, the previous tearing distance of 5 cms. being retained. Under these conditions the fraction of 73.4 per cent obtained in the second operation is increased to 88.7 per cent by this third operation while longer or shorter fibers occur no longer in any essential proportion.

Preferably after each tearing the sliver of fibers is subjected to a crimping.

The process described may be applied with ob vious modification to artificial fibers of any origin and suitable for ahy textile use.

What we claimlis:

1.1n the method of producing an extensible staple fiber sliver from a bundle of endless or continuous artificial fibers by tearing, said fibers having an extensibility of about 20 per cent, the improvement which comprises adJusting the draft applied to said bundle of endless fibers to between 1.3 and 2.0 while not substantially exceeding the limit of extensibility of said fibers whereby from about 28% to about 67% of the total staple fiber obtained is within the range of from 60-140 mm.

2. In the method of producing an extensible staple fiber sliver from a bundle of endless or continuous artificial fibers by tearing, said fibers having an extensibility of about 20 per cent, the improvement which comprises tearing said fibers with a draft not exceeding 1.3 whereby about 67% of the total staple fiber obtained is within the range of from 60-140 mm.

3. In the method of producing an extensible staple fiber sliver from a bundle of endless or continuous artificial fibers having an extensibility of about 20 per cent by tearing in several progressive stages, the improvement which comprises app1ying-.-for each tearing stage a draft 0! between 1.3 and 1.7, while not substantially exceeding the limit of extensibility of the said fibers whereby about 88% of the total staple fiber obtained is within the range of from 30-70 mm.

4. In the method of producing an extensible staple fiber sliver from a bundle of endless or continuous artificial fibers having an extensibility of about 20 per cent by tearing in three progressive stages the improvement which comprises applying a draft of 1.5 in the first tearing operation, a draft of 1.3 in the second tearing operation and a draft of 1.7 in the third tearing operation.

5. In the method of producing an extensible staple fiber sliver from a bundle of endless or continuous artificial fibers havingan extensibility of about 20 per cent by tearing in several progressive stages, the improvement .which comprises applying for each tearing stage a draft of between 1.3 and 1.7 and crimping after each tearing operation the extensible sliver produced.

6. In the method of producing an extensible staple fiber sliver from a bundle of endless or continuous artificial fibers having an extensibility of about 20 per cent by tearing in three progressive stages. the improvement which comprises applying a draft of 1.5 in the first tearing operation, a draft of 1.3 in the second tearing operation and a draft of 1.7 in the third tearing operation and crimping after each tearing operation the extensible sliver produced.

KARL xossnmam. PAUL BAFFER'I. 

